Frostbite.. what to do

Do you have good ventilation? The best way to prevent frostbite is to keep things as dry as possible, and vent the warm, moist air that the chickens are giving off.
Having said that, I always have a few birds that get some spots of frostbite each winter, especially those with large floppy combs. I usually just leave it alone, but some people put Vaseline on their combs to help prevent frostbite.
Good luck.
i will be glad when these below-zero nights are behind us!

 

do you have a pic of the coop? I'm no expert, but I read alot into this as its my first winter with chickens. there is some balance you need to find between good ventelation and no draft. As long as the moisture from breath, poop etc. has a place to exit, they should be ok.

Personally, I sealed up the windows and door with plastic and had hubby add a few screened pop vents along the ceiling line, seems to be working so far. Did the two that got frost bit have larger combs? I think thats also something that happens frequently in chickens with larger combs. at this point you just let it heal on it own. the black bits will fall off. some people, as a preventative, slather their combs with vaseline or bag balm when they know temps are dropping.